Declension table of ?mantravacana

Neuter	Singular	Dual	Plural
Nominative	mantravacanam	mantravacane	mantravacanāni
Vocative	mantravacana	mantravacane	mantravacanāni
Accusative	mantravacanam	mantravacane	mantravacanāni
Instrumental	mantravacanena	mantravacanābhyām	mantravacanaiḥ
Dative	mantravacanāya	mantravacanābhyām	mantravacanebhyaḥ
Ablative	mantravacanāt	mantravacanābhyām	mantravacanebhyaḥ
Genitive	mantravacanasya	mantravacanayoḥ	mantravacanānām
Locative	mantravacane	mantravacanayoḥ	mantravacaneṣu

Compound mantravacana -

Adverb -mantravacanam -mantravacanāt